Re: [PATCH/RFC] pmdomain: core: Support pd_ignore_unused with sync_state

[Geert Uytterhoeven]

Hi Ulf,

On Wed, 4 Mar 2026 at 12:52, Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote:
> On Wed, 4 Mar 2026 at 12:06, Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote:
> > On Wed, 4 Mar 2026 at 11:56, Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote:
> > > On Mon, 16 Feb 2026 at 19:47, Geert Uytterhoeven
> > > <geert+renesas@xxxxxxxxx> wrote:
> > > > Since the introduction of the sync_state mechanism, the
> > > > "pd_ignore_unused" kernel command line option doesn't really work
> > > > anymore.  While genpd_power_off_unused() still checks for that flag
> > > > before powering down unused domains, the new sync_state callbacks lack
> > > > such checks, thus powering down unused domains regardless.
> > > >
> > > > Fix this by adding checks to the sync_state helpers and callbacks.
> > > > Factor out the printing of the warning message, to make sure it is
> > > > printed only once.
> > > >
> > > > Fixes: 002ebddd695a5399 ("pmdomain: core: Restore behaviour for disabling unused PM domains")
> > > > Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
> > > > ---
> > > > RFC as I have no need for this in upstream.
> > >
> > > I am trying to understand the use case and whether we should consider
> > > to land this upstream.
> > >
> > > Would you mind elaborating on how this is useful for you?
> >
> > It is (currently) not useful for me, but it may be useful for others.
> > During work on a new SoC, someone had hardcoded "pd_ignore_unused"
> > in the kernel command line.  After adding support for PM Domains on
> > that SoC, I noticed PM Domains were still powered down.
> >
> > The issue is that pd_ignore_unused no longer does what it claims to do:
> >
> >         pd_ignore_unused
> >                         [PM]
> >                         Keep all power-domains already enabled by bootloader on,
> >                         even if no driver has claimed them. This is useful
> >                         for debug and development, but should not be
> >                         needed on a platform with proper driver support.
> >

[...]

> > So IMO that should either be fixed, or the option should be removed.
> > Do you agree?
>
> Right, I think it's time to consider removing it, unless people still
> find it useful ofcourse.
>
> Do you want to send a patch that we can test/review or you prefer me
> to handle it?

Feel free to handle it.
Thanks!

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds